Electroplating



Patented Aug.11, 1931 UNITED STATES PATENT OFFICE GEORGE LUTZ, F ROCKY RIVER, AND LEON R. WESTBEOOK, OF CLEVELAND HEIGHTS,

OHIO, ASSIGNORS, BY MFSNE ASSIGNMENTS, TO THE GRASSELLI CHEMICAL COM- PANY, OF CLEVELAND, OHIO, A CORPORATION OF DELAWARE ELECTROPLAI'ING No Drawing.

This invention relates to addition agents useful in the commercial production of electro lates on metals.

t is customary to add certain organic more I be obtained. The addition of such agents to' plating baths results, however, in electroplates of very desirable properties which could not be duplicated without them, and

hard, mirror-like perfectly adherent deposits are, in many instances, only due to the use of such addition agents. Such agents do not act the same in every type of bath or produce like results with all metals. It is usually necessary to adjust the composition of the bath'for every particular addition agent, and to duplicate or obtain uniform results strict adherence to the predetermined conditions is essential.

23 We have now found that certain alkylated naphthalene. sulfonic acids'and their water soluble salts are well suited for use as addition agents in electroplating processes.

. Alkyl naphthalene sulfonic acids in which 80 the alkyl group contains more than two carbon atoms are easily prepared and are commercially available in the form of their sodium salts. Propyl, butyl, cyclohexyl, and benzyl naphthalene sulfomc acids are typical representatives of this group of compounds.

Our invention consists now 'in the addition of relatively small amounts of such alkylated naphthalene sulfonic acids to electroplating baths and in the novel baths so obtained.

Electroplates obtained from such baths show usually an improved hardness, brightness, and better adherence of the-plate on the base metal.

The alkyl naphthalene sulfonic acids or their salts are so uble only to a limited extent in certain electroplating baths, in which instances the more soluble compounds, such as the benzyl-naphthalene sulfonic acids, are preferred as the amounts of the less soluble compounds which would 20 in solution might NaCN 120 Application filed February 23, 1928. Serial No. 256,476.

be insuflicient to produce the full beneficial effect obtained in our baths.

Valuable results have been obtained in alkaline cyanide baths as well as in acid baths. There a ain the composition of the bath as well as the particular alkyl naphthalene sulfonic acid used will have to be adjusted, and this can be done by a few experiments.

The following examples will further illustrate our invention by showing the application of the alkyl naphthalene sulfonic acids to various electroplating processes. It is understood that our invention is not limited to these particular baths, but that similar beneficial results can'be obtained in other electroplating as solutions by the addition pf alkyl naphthalene sulfionic acids thereto."

l) A cadmium cyanide bath wasprepared containing i grams Cd(OH) 48 grams Naso. 60 grams NiSOJH O 1. 5 grams per liter;

To this was added 1 gram of benzyl-naphthalene sodium sulfonate. This was electrolyzed with a current density of 15-30 amp. per sq. ft. at room temperature. A bright, hard, mirror-like plate was obtained on the steel cathode. I

The relative amounts of nickel and addition a ent are critical. 0.05% of theaddition agent to 0.005 to 0.03% of nickel in the bath glves the desired plate.

By doubling the amount of the naphthalene compound the amount of nickel has to be increased to 0.02 to 0.05% to obtain a similar result.

(2) 1 gram of benzyl-naphthalene sodium sulfonate was added to each liter of a nickel plating bath containing NiSOJH O 240 grams NiCl .6H O 15 grams H BQ 30 grams ZnSO .7H O 360 grams NH Cl 30 grams NaC H O .3H O 15 grams H SO. 3 grams Benzyl naphthalene sodium sulfonate 15 grams per liter.

The bath was kept at room temperature and a current density of 15-30 amps. per sq. ft. used. WVhiter, brighter and denser plates were obtained than without the use of the addition agent.

(4) Propyl-naphthalene sodium sulfonate was added in amounts varying from 1 to 2 grams per liter to a nickel plating bath containing NiSO /7H O 240 grams. NiCl fiH O 15 grams.

H BO 30 grams per liter.

The pH of this bath was adjusted to 5.8 and it was electrolyzed at a current density of from 520 amps. per sq. ft. at room temperature.

The addition of the naphthalene sulfonic acid to this bath had a decided beneficial effeet in that the plates obtained on steel were brighter, smoother, more uniform, and harder than plates obtained without the use of the addition agent. They were quite similar to those obtained with the benZyLnaphthalene sulfonic acid.

(5) The addition agent used in Example 3 was replaced in the same bath by propylnaphthalene sodium sulfonate in amounts from 1 to 5 grams per liter, maintaining other conditions alike. The plates on steel were decidedly brighter and whiter than those obtained from the same baths in which the addition agent had been omitted.

It is immaterial, for purposes of this invention, whether the free alkyl-naphthalene sulfonie acids or their water soluble salts are used as addition agents to electroplating baths; the actual compound contained in the bath will depend upon the alkalinity or acidity of the bath, and the term alkyl naphthalcnc sulfonic acid as used herein is meant to embrace the free acids as well as their water soluble salts or derivatives. It is furthermore understood that the term alkyl, as used herein, includes ar-alkyl radicals such as benzyll and other saturated hydrocarbon radica s.

We claim 1. An alkyl-naphthalene sulfonic acid as an addition agent to an electro lating bath. 2. An alkyl-naphthalene sul onic acid, in which the alkyl group contains more than two carbon atoms, as an addition agent to an electroplating bath.

3. An electroplating bath comprising an aqueous solution of a compound of a metal to be deposited by electrolysis, said solution conaining an alkyl-naphthalene sulfonic aci 4. An electroplating bath comprising an aqueous solution of a compound of a metal to be deposited by electrolysis, said solution containing an alkyl-naphthalene sulfonic acid in which the alykyl group contains more than two carbon atoms.

5. The process of electroplating which comprises electrodepositing a metal from an aqueous solution of a compound of a metal to be deposited, said solution containing an alkyl-naphthalene sulfonic acid.

6. The process of electroplating which comprises electrodepositing a metal from an aqueous solution of a compound of a metal to be deposited. said solutions containing an alkyl-naphthal-ene sulfonic acid in which the alkyl group contains more than two carbon atoms.

7. An aqueous cadmium cyanide electroplating bath containing in solution an alkyl naphthalene sulfonic acid compound in which the alkyl group contains more than two carbon atoms.

8. An aqueous nickel electroplating bath containing in solution an alkyl napthalene sulfonic acid compound in which the alkyl group contains more than two carbon atoms.

9. An aqueous acid zinc electroplating bath containing in solution an alkyl naphthalene sulfonic acid in which the alkyl group contains more than two carbon atoms.

In testimony whereof, we aflix our signatures.

GEORGE LUTZ. LEON R. WESTBROOK. 

